One Piece: Infinite Treasure Chest System.

With Higuma incapacitated, Ben had no trouble rescuing the remaining prisoners. By the time the bandits realized what had happened, Ben was long gone.

After settling that matter, Ben set his sights on the island's only Silver chest. Now that he had Armament Haki, he was eager to see what treasures awaited him.

This is the last chest on the island, which means I'll get another Special Chest as a reward. Last time, I got the Water Dragon's Affinity. Maybe my luck will hold out this time too.

The thought of a Silver chest and a Special Chest was too tempting to resist.

Soon, Ben arrived at the entrance of a massive cavern. The sight reminded him of the giant lizard he'd encountered earlier, but this cave was far larger. Who knows what's lurking inside?

After some hesitation, Ben decided he couldn't leave without at least scouting the area.

"Water Pulse: Condense!"

Ben activated his most powerful controllable skill with Water Dragon's Affinity, drawing water from a nearby lake and sending it surging into the cave.

"Moo!"

A deep, resonant bellow echoed from within, followed by tremors that shook the ground.

Realizing the danger, Ben turned and ran. Whatever was inside was far beyond his current capabilities. He hid in the canopy of a large tree, watching the cave entrance from a safe distance.

What emerged next nearly stopped his heart.

A massive head, the size of a shipping container, poked out of the cave. Even from a distance, Ben could see the creature's ox-like features.

Thankfully, the beast only lingered for a moment before retreating into the cave. Ben let out a shaky breath. No way am I going near that thing. I'll ask Dadan about it later.

After returning to Dadan's house, Ben went straight to Dadan.

"Boss Dadan, here's my rent for staying here."

Ben walked in and placed a large bag in front of Dadan.

"Kid, how much could you possibly have? This bag better not be full of foam," Dadan said skeptically, reaching for the bag to set it aside.

But the moment she picked it up, her expression changed. The bag was heavy.

"There's 500,000 berries in there. It's not much, but I can't stay here for free," Ben said casually.

"Alright, kid, what do you want from me?" Dadan set the bag aside and crossed her arms.

"That cave on top of Mount Colubo…"

"Kid, don't tell me you messed with that thing?" Dadan interrupted, her face turning serious.

"Uh, not exactly. I just flooded its cave with water. I wanted to know… what kind of creature is that?" Ben scratched the back of his head, looking a little embarrassed.

"You… you've got some nerve. 100,000 berries, and I'll tell you," Dadan said, holding out her hand.

"Deal." Ben handed over another bag of money.

"You've got more?!" Dadan was surprised. She'd thought Ben was out of cash and would drop the subject. "Fine. That's the Azure Ox-Serpent. It's an ancient creature. I've never seen it fight, but it's at least as strong as a Rear Admiral. So, unless you've got a death wish, stay away from it."

Ben's heart sank. A Rear Admiral-level creature? I can barely handle a few bandits. How am I supposed to deal with that?

Two weeks had passed since Ben learned about the Azure Ox-Serpent. During that time, he'd come to appreciate just how valuable the Progress Boost Card he'd used earlier was. A 10% boost in proficiency was nothing short of miraculous.

After half a month of intense training, Ben's Armament Haki proficiency had only increased to 16%. Still, he'd grown more familiar with his abilities and was steadily improving.

"Three hundred fifty-eight, three hundred fifty-nine…" Ben was in the middle of a grueling workout. While he focused on strengthening his body, he also continued to train his Haki.

"Five hundred!"

After finishing his five hundredth push-up, Ben pulled out Senbonzakura. Though he didn't understand why he could use it without entering a soul form, he wasn't about to question his luck.

He began his sword training, determined to master Senbonzakura.

"Shikai: Scatter, Senbonzakura!"

The blade in Ben's hand dissolved into countless tiny petals, shimmering like cherry blossoms in the sunlight.

"Hah!"

With a shout, the petals surged forward, slicing through a large tree. When the blade reformed, the tree was reduced to splinters.

"It's time. Time to claim that Silver chest."

Ben set off for Mount Colubo, his confidence bolstered by his newfound strength.

Unbeknownst to him, Dadan appeared shortly after he left. She picked up a piece of the shattered tree, her expression a mix of shock and curiosity.

When Ben reached the cave, he activated Water Pulse: Condense once more. It was safer to lure the creature out than to face it in the dark confines of the cave.

"Moo!"

The familiar bellow echoed from within, followed by the ground-shaking footsteps of the Azure Ox-Serpent.

Ben gripped Senbonzakura tightly and crouched low, waiting for the creature to emerge.

The massive ox-like head appeared, its eyes scanning the area.

"Shikai: Scatter, Senbonzakura!"

Ben unleashed Senbonzakura's Shikai, sending a flurry of blade petals toward the creature.

"Clang! Clang! Clang!"

The petals struck the Ox-Serpent's hide, but to Ben's dismay, they barely left a scratch.

Realizing the danger, Ben rolled to the side just as the creature's tail slammed into the ground where he'd been standing, leaving a deep trench.

That would've crushed me, even with Armament Haki, Ben thought, his heart racing.

"Moo!"

The Ox-Serpent roared, its tail whipping toward Ben again. This time, Ben was ready.

"Water Prison: Bind!"

Ben activated Water Dragon's Affinity, but instead of targeting the Azure Ox-Serpent, he encased himself in a protective water barrier.

"Pop!"

"Boom!"

The barrier shattered under the Ox-Serpent's tail, sending Ben flying.

"Ugh!" Ben spat out a mouthful of blood as he struggled to his feet, leaning on Senbonzakura for support.

He'd just experienced the true power of a Rear Admiral-level creature. It was like fighting a god—there was no contest. Whether it was speed, strength, or defense, Ben was completely outclassed.